Add using alternative branch support for custom indexes

cmd/krew/cmd/index.go

@@ -64,9 +64,13 @@ each configured index in table format.`,
 }
 
 var indexAddCmd = &cobra.Command{
-	Use:     "add",
-	Short:   "Add a new index",
-	Long:    "Configure a new index to install plugins from.",
+	Use:   "add",
+	Short: "Add a new index",
+	Long: `Configure a new index to install plugins from.
+
+This command also supports alternative branch other than the default one
+by appending the branch name to the end of git url with # symbol
+(e.g. /kubernetes-sigs/krew-index.git#another_branch).`,
 	Example: "kubectl krew index add default " + constants.DefaultIndexURI,
 	Args:    cobra.ExactArgs(2),
 	RunE: func(_ *cobra.Command, args []string) error {

internal/gitutil/git.go

@@ -31,7 +31,12 @@ func EnsureCloned(uri, destinationPath string) error {
 	if ok, err := IsGitCloned(destinationPath); err != nil {
 		return err
 	} else if !ok {
-		_, err = Exec("", "clone", "-v", uri, destinationPath)
+		parsedURI := strings.Split(uri, "#")
+		if len(parsedURI) > 1 {
+			_, err = Exec("", "clone", "-v", "--single-branch", "--branch", parsedURI[1], parsedURI[0], destinationPath)
+		} else {
+			_, err = Exec("", "clone", "-v", uri, destinationPath)
+		}
 		return err
 	}
 	return nil

internal/index/indexoperations/index_test.go

@@ -102,6 +102,21 @@ func TestAddIndexFailure(t *testing.T) {
 	}
 }
 
+func TestAddIndexFailureWithCustomBranch(t *testing.T) {
+	tmpDir := testutil.NewTempDir(t)
+
+	indexName := "foo"
+	localRepo := tmpDir.Path("local/" + indexName)
+	tmpDir.InitEmptyGitRepo(localRepo, "")
+
+	paths := environment.NewPaths(tmpDir.Root())
+
+	localRepoWithBranch := localRepo + "#test_branch"
+	if err := AddIndex(paths, indexName, localRepoWithBranch); err == nil {
+		t.Errorf("expected error test_branch not found")
+	}
+}
+
 func TestDeleteIndex(t *testing.T) {
 	// root directory does not exist
 	if err := DeleteIndex(environment.NewPaths(filepath.FromSlash("/tmp/does-not-exist/foo")), "bar"); err == nil {